CAPN 8: Isolation of a new mouse calpain-isoenzyme

Recent molecular biological approaches indicate that calpain, also named CA NP for calcium-activated neutral protease and originally characterized as a n intracellular cytoplasmatic nonlysosomal cysteine protease that requires calcium ions for activity, constitutes a large superfamily consisting of ub iquitous and tissue specific homologues, which are widely distributed in ce lls of various organisms from human to fungus. Due to the increasing number of substrates along with the involvement of calpain isoenzymes in mammalia n diseases, especially in malignancies, members of the calpain superfamily seem to be important biomodulators in physiological as well as pathological cell function. Here we report the characterisation of a new calpain, named CAPN 8 with a different C-terminal domain, implicating a putative new regu latory mechanism. Northern blot analysis revealed an ubiquitous expression with different RNA levels in all tissues examined. Highest levels were foun d in brain, kidney, and digestive tract, suggesting a specific regulatory f unction of CAPN 8 in these tissues. (C) 1999 Academic Press.